In a stringed musical instrument, such as a guitar, the strings extend unsupported between a first critical point usually formed by the nut where the neck joins the head and a second critical point usually formed by the bridge positioned on the body. The strings are anchored at one end on a portion of the instrument known as the tailpiece, strung over the bridge and the nut on the head of the instrument and in conventional instruments anchored on the other end to the tuning pegs where an untensioned string is tensioned and adjusted to a tuned condition. The second critical point is formed by a part of the bridge or by a part of a combined bridge and tailpiece structure. Traditionally, the size of the bridge elements are quite small so as to create a clearly defined single point of contact between the string and the bridge element. It is between these two points that the string length is determined. This is sometimes referred to as the scale length. Adjusting the relative distance between the first and second critical points is called harmonic tuning. Some bridges structures have individually adjustable bridge elements for further refining the harmonic tuning. Additional means for the adjustment of the height of each bridge element relative the body of the instrument is often provided. The typical construction of the strings, particularly for guitar and bass, have a plain end and a xe2x80x9cball endxe2x80x9d in which a washer-like addition is wrapped by the string itself as a means to secure the string to the instrument on the tailpiece. The wrapping usually extends xc2xdxe2x80x2 towards the plain end and as such the tailpiece structure must insure that the wrapping does not extend over the second critical point when arranged on the instrument. Fine tuning has been a long standing problem for stringed musical instruments.
It is known to those skilled in stringed musical instrument design and construction that combining the bridge and the tailpiece can be advantageous and that, additionally, various tremolos have been proposed and utilized for varying the tension of all the strings simultaneously for the purpose of creating a tremolo sound. Further, it is known to those skilled in the art that there are a great many commonly used names for such devices, such as tremolo, tremolo device, tremolo tailpiece, tremolo bridge, fulcrum tremolo, fulcrum tremolo bridge, fulcrum tremolo tailpiece, fulcrum tremolo bridge-tailpiece, vibrato, vibrato bridge, vibrato tailpiece, vibrato bridge tailpiece, etc.
Many manufacturing techniques have been employed in the construction of such devices and vary from stamping and folding on one end to casting and machining of parts on the other end.
In one specific species, known as the fulcrum tremolo, Fender U.S. Pat. No. 2,741,146, shows and provides a tremolo device which incorporates a novel bridge structure and the tailpiece, commonly known to specifically provide the anchoring means for the strings. The bridge plate is also known as the base plate. The base plate upon which the individual bridge elements are adjustably secured has a beveled ridge portion which is secured to the instrument body by six screws for permitting pivotal movement about a fulcrum axis which varies the tension on the strings and produces the desired tremolo effect. Further, the bridge and the tailpiece both move together as the tremolo device is pivoted. The bridge elements are stamped and folded into a suitable form and are loosely held in place by a spring loaded attachment screw arrangement until the instrument is strung; the attachment screws are secured through openings in a small folded ridge portion of the base plate farthest from the fulcrum axis. The bridge elements also incorporate set screws for varying the relative height of the bridge elements to the base plate bringing the number of parts for the six bridge elements to 30 or 5 part per bridge element assembly.
Typically, when a fulcrum tremolo pivots about its fulcrum axis, counter springs are utilized to counteract the pull of the strings. Counter springs are usually connected to the body of the instrument at one end and to a separate spring attachment means, usually called a spring block, fashioned often from a block of milled or cast steel and secured to the bottom of the base plate by three screws bringing the total including the mounting and tremolo arm assembly of the individual parts to the whole assembly to 43. Other design for similar tremolos have had as many as 8 parts per bridge assembly.
Improvements to Fender U.S. Pat. No. 2,741,146 fulcrum tremolo have included using string locks at the nut and immediately behind the second critical point on each of the bridge elements to limit string stretch to within these two points to improve the return to initial position after pivoting the tremolo device (Rose U.S. Pat. No. 4,171,661). Using the string locks required removing the ball end of the string for installation on the tremolo. In Rose U.S. Pat. No. 4,497,236 a combination of the bridge element, the tailpiece and fine tuners replaced the xe2x80x9cnovel bridge structurexe2x80x9d incorporating the tailpiece of the Fender device so that within the limited range (typically less than a whole tone) the strings could be re-tuned without unlocking the string clamps at the nut. The fine tuner arrangements comprised seven parts per string and four of the parts are either machined or cast bringing the total number of parts of the tremolo to over 60. Additional improvements provided for a xe2x80x9cknife-edgexe2x80x9d pivot means where each of two screw-like posts received a corresponding beveled edge of the base plate. These screw-like posts were positioned about 2.925xe2x80x3 apart and had a broad spacing. Further refinements to the Fender fulcrum tremolo included a similar arrangement with the screw-like posts positioned about 2.22xe2x80x3 apart, having a narrow spacing and created a second standard. The parts of the two competing designs were not compatible. Consequently, those who had guitars with the 2.925xe2x80x3 spacing were limited to tremolos that had fine tuner arrangements and string locks and those guitars with the 2.22xe2x80x3 spacing were limited to those tremolos without fine-tuners and string locks.
The evolution from fine tuners to macro-tuners on a fulcrum tremolo (McCabe U.S. Pat. No. 5,986,191, Nov. 16, 1999) provided an intonation module that included a novel integrated one piece bridge-tailpiece structure secured to the base plate wherein the improvement included the means to bring and adjust the strings to playing pitch from an untensioned condition circumventing the re-tuning limits imposed by the fine tuner arrangements. Further, the improvement comprised xe2x80x9cclampingxe2x80x9d the string between the second critical point and the anchor point so the length of the string in the direction of the anchor point is substantially inextensible. The replacement of fine tuners with macro-tuners on a fulcrum tremolo (McCabe U.S. Pat. No. 5,965,831, Oct. 12, 1999) provided an alternative means wherein the improvement comprised gripping the string between the second critical point and the anchor point and eliminated string stretch in the direction of the anchor point. In each case the clamping or gripping means moved between two creative positions as the adjustment knob was adjusted to achieve macro-tuning. The macro-tuner arrangements although containing 25-50% fewer parts than fine tuner arrangements still comprised parts mostly either machined or cast.
Macro-tuners refer to tuners with the capacity to raise and adjust the tension of the strings from an untensioned condition to a proper playing pitch, and as such provide for alternate tunings and compensation for substantial string stretch during the life of the string essentially without additional means.
Therefore, for stringed musical instruments, as is known to those skilled in the art:
the second critical point is a clearly defined point on the bridge or individual bridge elements, the adjustment of which relative to the first critical point on the nut defines the length of the string or scale length and is called harmonic tuning;
for fulcrum tremolos as originated by Fender U.S. Pat. No. 2,741,146, the bridge elements were stamped and folded and when pivoted:
the bridge elements, the string anchoring means, base plate and the spring anchoring means simultaneously move about a fulcrum axis; and
there is a tendency for the harmonic tuning to be upset;
for those fulcrum tremolos equipped with fine tuners or macro-tuners,
the fine tuners or macro-tuners simultaneously move with the bridge and tailpiece portions about the fulcrum axis when the device is pivoted;
for those fulcrum tremolos fitted with string locks at the first and second critical points as in Rose U.S. Pat. No. 4,171,661,
string stretch beyond the locks at the first and second critical points is eliminated offering a stability of tuning for the set of problems associated with string stretch; and finally,
for those fulcrum tremolos fitted with macro-tuners:
the gripping or clamping portions are arranged such that the length of string in the direction of the anchor point is substantially inextensible;
employing the adjustment knob of the macro-tuner moved the gripping or clamping means.
McCabe U.S. Pat. No. 6,175,066 and McCabe International Patent Application No. PCT/US98/20376 show various embodiments of bearing arrangements within housings and are supported on the instrument body by adjustable riser posts providing means for changing the height of the bass and treble side of the tremolo relative to the instrument body. The riser posts are provided with an annular flange upon which each relative bearing housing rests. However, there are neither means for securing the adjustment of the relative distance between the bearing inner ring and the annular flange of the bearing axle for balancing the load on the bearings nor means for compensating variations in distance between riser posts from one instrument to another.
In McCabe International Patent Application No. PCT/US98/20376 more comprehensive methods of folding metal to reduce the number of parts were introduced. McCabe integrated the spring block into the sheet metal base plate material where an additional brace was bend outwardly towards the pivot axis from the resulting spring blade and which was held in place by an attachment screw. Other features included bending the portion of the base plate closest to the bearing axis nearly 180 degrees forming a structure secured by additional attachment screws which when drilled transversely received the bearing axle. Other features included xe2x80x9ccoiningxe2x80x9d the base plate in a series of tiers for both displacing the heights of the intonation modules relative to the base plate or the instrument body to account for the radius of the fretboard. This eliminated the need for individual bridge element height adjustment screws so that the entirety of the bridge elements rest on the base plate maximizing acoustic coupling between the two and reducing part count. xe2x80x9cCoiningxe2x80x9d refers to that process in the stamping of metal that provides for a xe2x80x9creliefxe2x80x9d or xe2x80x9clandscapexe2x80x9d in the object being formed.
Accordingly, the primary object of this invention is to provide additional improvements to the folded techniques for the integrated base plate and spring blade arrangement with an alternative means to reinforce the position of the spring blade relative the base plate and adapt the folding techniques to a novel intonation body. Reducing the number of parts improves the sonic character of the musical instrument and lowers the cost of manufacture. A separate support insert is formed with two tabs fitting into respective openings of the base plate portion and the spring blade portion. The separate support insert is sprung into place and held secure using the tabs and their respective openings. Alternatively, a single tab could be used in a brace formed from either the base plate or spring blade portion. Additionally, incorporating raised ribs or pins in the base plate can mate to similar raised ribs or recesses in the bottom of intonation modules.
It is a further object of the invention to provide folded intonation modules integrating the bridge and the tailpiece functions and include a second portion that creates an additional contact point or area between the second critical point and the string anchoring means that grips the string as it is tensioned to pitch. The folded intonation modules have an opening in the end furthest the second critical point for inserting the string through a small opening into a pop-up tab in the mid-section of the base sufficient in size to restrict the ball end of the string thereby creating the anchoring means. As the string is tensioned an increasingly greater force is applied to the string against the additional contact gripping means. Such a point or area is arranged such that the length of string in the direction of the anchor point is substantially inextensible when the string is tuned. Accordingly, the additional contact point or area is positioned as close to the second critical point and base plate as possible for gripping the string sufficiently to keep the tuning of the string stable throughout the performance range of the tremolo on the hand while balancing the need for the threading and tuning of the string on the other. Such an arrangement is referred to as a StringClip.
Further, the folded intonation modules body integrates the tailpiece and bridge and features a tab and slot construction means as well as reinforcement ribs on the bottom portion of the intonation body. The ribs can strengthen the structure and double in function when positioned over smaller ribs or pins formed in the base plate to align the intonation module into position for fine tuning the harmonic tuning of the assembly.
Another object of the invention is to integrate a novel macro-tuner means with the folded intonation modules that includes a second portion providing a StringClip. The macro-tuner means employs a pin-like string holder element which provides the anchoring means or tailpiece function at one end and an adjustment knob threadedly engaged with the string holder element for positioning the string holder element and, therefore, the anchor point, relative to the second critical point for macro-tuning. Additionally, the string holder element has a first creative position closer to the second critical point when the string is in a low or no tensioned condition and can be threaded through the intonation body without engaging the gripping means. The string holder element has a second creative position further the second critical point holding the string in a tensioned condition where the tension of the string proportionally engages the gripping means and renders this portion of the string substantially inextensible in the direction of the anchor point from the second critical point.
The string holder means includes a flattened portion along the length of a pin-like portion. Integrated into the folded intonation module is a mid-body tab with an restricted opening arranged to direct the flattened portion of the pin-like portion past the attachment screw while providing support for the string holder element and simultaneously limiting the rotation of the string holder element as the adjustment knob is threaded.
Additional features found in the folded intonation module include a support tab fashioned from the second portion which is then inserted into a slot formed for strengthening the structure to a level of rigidity necessary for handle the loads of the string tension during the pivoting of the tremolo. An alternative method is also shown which require welding a support tab to the second portion.
It is a further object to provide a modular fulcrum tremolo system with standardized base plate features available both the 2.925xe2x80x3 spacing and 2.22xe2x80x3 spacing where all the additional parts, such as the intonation modules solid or folded, with or with out macro-tuners, the global tuners, the tremolo arm assembly, etc. are interchangeable. Consequently, anyone can have simple intonation modules or macro-tuners regardless of the spacing size present on the instrument.
It is another object to provide improvements to the integrated base plate/spring blade structure where a concave radius is formed in the base plate at the end closest to the bearing axis to fully receive and align the position of the bearing axle which then can be secured by spot welding, brazing or other similar means.
Yet, another object of the invention is to provide an improved bearing housing arrangement that utilizes a set screw adjustably secured within the section of the bearing housing that receives the riser posts. The riser posts include a groove in the circumference of the portion of the riser post that is positioned relative to the tip of the set screw. The set screws are adjustably positioned against the circular indent in the riser posts for:
limiting the position of the bearing housing relative to the annular flange of the riser posts;
providing lateral adjustment of the position of the bearing housing relative to the riser post annular flange optimizing the load on the bearings; and
adapting to anomalies in the distance between the two riser posts from instrument to instrument.
Although the above improvements are featured in the preferred embodiment, intonation modules with the additional contact point or area can comprise the bridge elements or tailpieces alone, combination bridge-tailpieces and can be used for tremolos and non-tremolo devices. Similarily, coining tiers into the base plate and other stamping features can be adapted to non-tremolo bridge and bridge-tailpieces.